1. Field of the Invention
The invention relates to a valve for a pressure container, such as a keg of beer, according to the preamble of claim 1.
2. Description of the Related Art
Such a valve is known, e.g. from U.S. Pat. No. 4,509,663 and GB-B-2 192 621. With both valves, the pressure relief opening is formed by the gap that has formed as a result of play between the inside of the neck ring and the outside of the inner part. According to GB-B-2 192 621, said gap is 0.02-1.0 mm wide, which should be enough to provide a sufficiently quick pressure relief. However, there is a danger that the sealing ring which is disposed in said gap will seal the gap as a result of being pressed upwards and becoming wedged in said gap upon movement of the inner part during the first step. With the valve according to said British patent an additional cam is indeed provided on the inner side of the neck ring, which cam should at least partially prevent said phenomenon from occurring, but in practice it has become apparent that in some situations, in particular at high pressures, the sealing ring nevertheless seals the passage between the pressure ring and the inner part in such a manner that this interferes with the pressure relief.